Wordpress problem uploading new media : File is empty. Please upload something more substantial

I'm running a 4.1.1 Wordpress without plugins and while trying to upload an image (2mb in this exemplary case) I get:

    'http error'

when I retry it returns

has failed to upload due to an error File is empty. Please upload something more substantial. This error could also be caused by uploads being disabled in your php.ini or by post_max_size being defined as smaller than upload_max_filesize in php.ini. '

I have googled (of course) and checked my php.ini settings using phpinfo inside the /wp-content directory.

    file_uploads on
    memory_limit 128M
    upload_max_file_size 25M 
    post_max_size 25M

The permissions on /wp-content as well as /wp-content/uploads are in order. the tmp directory is writable and the disk is not full.

I have walked through these 2 questions arlready:

• WordPress File Upload always give PHP.ini error (Updated)


• Error “file is empty” when uploading images in WordPress

Not going to mention all Wordpress forum posts and not running on bluehost or anything like that. Running on my own iron box (Debian)

Any clues?